Devices that might be used by users in a telecommunications network can include both mobile terminals, such as mobile telephones, personal digital assistants, handheld computers, and similar devices, and fixed terminals such as residential gateways. Such devices, which will be referred to herein as user devices, sometimes need to securely store private data. For example, the credentials a user device uses to gain access to network services typically need to be safeguarded against unauthorized use. Other examples of private data that might be stored on a user device include passwords, credit card numbers, contact information, device settings, encryption keys, and text-based data.
Currently, such private data might be stored on a subscriber identity module, or SIM card, that can be inserted into a user device. The use of a SIM card allows a user to easily transfer private data from an older user device to a newer user device upon the purchase of the newer device. SIM cards also allow a first user to use a user device belonging to a second user by simply inserting the first user's SIM card into the second user's device. Charges for a call can then be assigned to the first user even though the first user is using the second user's device.
While promoting the portability of data in this manner, SIM cards can also present some drawbacks. For example, the hardware-based SIM cards can increase the cost of a user device and can be cumbersome to provision, distribute, and modify. Also, data stored on a SIM card can be susceptible to theft since the card can be removed from a user device and read by another device or by a SIM card reader.